Pemphigus Complex

What is it?

Pemphigus is an autoimmune skin disease: the body's immune system attacks the "glue" that holds skin cells together, so the skin separates and forms pustules, crusts, ulcers, or blisters. Most cases have no known cause. Some are linked to genetics, chronic skin allergies, cancer, UV light, or drug reactions. Autoimmune skin diseases are rare overall in dogs. The main forms are:

Pemphigus foliaceus (the most common)

Pemphigus foliaceus (PF) is the most common autoimmune skin disease in dogs, often seen in middle-aged and older dogs. It causes crusts (scabs), hair loss, and sores around the eyes, ears, face, bridge of the nose, footpads, and groin, and can spread over the body. It often appears suddenly without a known cause, but can be drug-induced or follow years of skin disease. Breeds more often affected include the chow chow, Akita, cocker spaniel, Labrador retriever, dachshund, English bulldog, Finnish spitz, and schipperke.

Pemphigus vulgaris

Pemphigus vulgaris (PV) is rare in dogs but is the most severe common type, because it attacks the deepest layer of the outer skin. Fluid-filled blisters form in and around the mouth, eyelids, lips, nostrils, anus, and genitals, then break open into painful ulcers.

Pemphigus erythematosus

Pemphigus erythematosus (PE) looks like a milder pemphigus foliaceus, with redness, crusting, scaling, and hair loss, especially on the nose. UV light makes it worse. German shepherds, collies, and Shetland sheepdogs are predisposed.

Paraneoplastic pemphigus

Paraneoplastic pemphigus (PNP) occurs with an underlying malignant tumor. It is the least common and most severe form.

What signs should I watch for?

Watch for crusts, scabs, pustules, hair loss, or sores on the face, ears, nose, and footpads, thickened or crusty pads, and, with the rarer forms, blisters or ulcers around the mouth, eyes, or other body openings. Any crusting or ulcerated skin that does not heal should be checked.

How is it diagnosed and treated?

A skin biopsy, taken with a small punch under local anesthesia or sedation, is needed to diagnose pemphigus and its type. Treatment suppresses the immune system, usually with corticosteroids such as prednisone and sometimes other immune-suppressing drugs such as azathioprine, chlorambucil, or cyclosporine. Antibiotics or medicated baths treat secondary infection. Treatment is often long-term or lifelong, with regular rechecks to find the lowest effective dose and watch for side effects.

Can it be prevented, and what's the outlook?

• Most cases cannot be prevented, though suspected drug triggers should be stopped.
• Outlook depends on the type: pemphigus erythematosus usually responds very well, and pemphigus foliaceus has a relatively good outlook, with some dogs eventually weaned off medication and others needing lifelong treatment.
• Pemphigus vulgaris has a poor outlook and is often fatal despite treatment, and paraneoplastic pemphigus is the most severe form.